Last week was a big one in our household.
My son competed in his first ever track and field meet, running the second leg of the 4x100. It was his first time in a baton handoff, first time in spikes, first time feeling that pre-race nervous energy… and his team won. Proud dad humble brag.
As if that wasn’t enough, it also happened to be National Biomechanics Day last week, a celebration of the science behind human movement. So naturally, I’ve been thinking a lot about how we move — and more importantly, how we move faster.
Which brings me to a recent research paper I read:
"How Humans Run Faster: The Neuromechanical Contributions of Functional Muscle Groups to Running at Different Speeds" published in the Scandinavian Journal of Medicine & Science in Sports.
It’s a mouthful, but stick with me — this one’s gold for coaches, sport scientists, and strength professionals.
How We Speed Up
The researchers analyzed runners from 2.78 m/s (easy jog) up to 8.33 m/s (near sprint) on a force-measuring treadmill while monitoring muscle activation, joint moments, and mechanical work using kinematics and EMG.
Here’s what they found:
✅ At slower speeds, running is mostly powered by the ankle plantar flexors (think your calf and Achilles system), which generate over 60% of the energy during stance.
✅ But as speed increases, the hip extensors (your glutes and hamstrings) take over. At high speeds (above 5 m/s), they become the primary source of forward propulsion — especially during the swing phase where their contribution increases twelvefold.
✅ The knee flexors (hamstrings again) become critical in absorbing energy (yeah, I know, you can't "absorb" energy - don't @ me!) at high speeds, showing superlinear increases in negative work, which has huge implications for hamstring injury risk and eccentric strength training.
✅ Step length increases early, but at top speeds, it’s step frequency that drives performance — and that’s tightly linked to hip extensor output in swing.
So What? Why This Matters for S&C and Sport Science
This paper gives us clean, quantifiable evidence for how different muscle groups contribute at different speeds:
- For field sport athletes, training the hip extensors for explosive swing-phase propulsion is critical.
- For sprinters, eccentric hamstring strength (especially late swing) is non-negotiable.
- For endurance athletes, knowing when plantar flexors plateau may inform transition strategies for mid-race surges or kick phases.
- For return-to-play, we can’t just test top-end speed — we need to understand how muscle group contribution shifts across velocities.
It also gives us a research-backed explanation for why younger athletes (like my son!) often sprint by just opening up their stride… but eventually need to develop coordination and strength around frequency, not just length.
Practical Takeaways for the Weight Room
- ✅ Train hip extension under speed — think band-resisted sprint drills, sled pushes, high-speed treadmill work, or fly-in sprints.
- ✅ Build eccentric knee flexor strength — Nordics, razor curls, or sprint decelerations.
- ✅ Don’t neglect calf/Achilles stiffness — even though it peaks early, it still contributes meaningfully throughout.
Watching my son compete for the first time reminded me that speed isn’t just talent — it’s layers of coordination, timing, and muscle contributions working in harmony. And now we’ve got even more science to help us understand how it all clicks.
Here’s to the next generation of runners… and the science that helps them go faster, stronger, and safer.
